On Friday May 22, Ireland will become the first country in the world to hold a referendum on marriage equality, with the result due on Saturday. Irish citizens will be asked to vote Yes or No on the following proposed amendment to Article 41 of the Constitution:

Marriage may be contracted in accordance with law by two persons without distinction as to their sex.

While the Yes side has held a clear majority in opinion polls for months, there is some nervousness about the polls’ reliability, as the gap has narrowed significantly in the final days.

In light of the UK election result – particularly the failure of every publicly available poll to accurately predict the Conservatives’ win – there is still the possibility that the Irish referendum will be much closer than the polls suggest.

That’s what the No campaigners have long been predicting. Last month, Mothers and Fathers Matter spokesman Keith Mills said early polling on referendum votes were “notoriously unreliable”, and that:

There has consistently been, on no matter what issue, a swing back to the status quo in the last month of the campaign.

In 1995, Ireland held a referendum to allow divorce. In the lead-up to the vote the Yes side held a huge, double-digit lead in the polls. But much like the current marriage equality referendum, the No side worked hard to raise doubts in voters’ minds – and in the end, the Yes campaign won with just a 0.6 percentage point margin.

For both the Yes and No camps, the key focus is now on getting people out to vote on Friday: a final push that could decide the result.

Creative campaigning

This has been a campaign full of creativity and artistic contributions. Social media has been central to getting the message out by both sides, which have run very different campaigns.

The “Yes Equality” side has run a nationwide grassroots canvassing campaign, encouraging supporters to door knock and share their personal stories to change hearts and minds.

The No campaign has been described as “more "muted” by The Irish Times. One of the leading groups on the No side has been Mothers and Fathers Matter, which says the referendum is “not about gay rights” but about protecting the institution of marriage, as well as “family and children and mothers and fathers”.

Hundreds of thousands of people have watched online videos such as Mrs Brown’s contribution as the “mammy in chief” (backing a Yes vote) and the Mothers and Fathers Matter video (encouraging a No vote).

There have also been celebrity and sporting endorsements on both sides. Among the most notable has been singer Daniel O’Donnell, who has a large fanbase in rural Ireland. He came out in favour of a Yes vote.

The case for No

Mothers and Fathers Matter

In Ireland, for each referendum, an independently appointed referendum commission is tasked with providing voters with impartial information about the referendum. The commission chairman - a High Court judge - has stated: “Parental rights will not be changed by a vote one way or the other.”

Despite this, the No campaign has focused on children and defending the traditional view of marriage. Or as the Iona Institute, a religious think-tank, puts it in this video: “Marriage equality = inequality for children”.

Why Vote No? The one-minute reason from the Iona Institute.

At the Mothers and Fathers Matter campaign media launch, unsubstantiated claims were made that children raised without a father were “more prone to crime”.

High-profile religious figures have come out for both the No and Yes camps.

But while the Yes campaign has dominated some areas of social media, such as Twitter, an evangelical Christian alliance is also tapping into technology, sending out messages via Whatsapp to tens of thousands of Irish voters.

New Irish migrants could prove crucial in the referendum. The Guardian has reported that an evangelical Christian alliance is banking on persuading up to 200,000 African and eastern European immigrants to vote No.

The case for Yes

EPA/Aidan Crawley

All of Ireland’s major political parties are advocating a Yes vote, as are the main civil society organisations, trade unions and most notably the leading children’s charities.

Earlier this week, the former president of Ireland, Mary McAleese – a practising Roman Catholic – stated that the referendum is about Ireland’s gay children and about their future.

For the Yes side, the success or failure of this referendum will come down to personal stories.

The most recent came from Ursula Halligan, the widely recognised political editor of TV3, who has come out in The Irish Times.

Halligan wrote that she had been resigned to going to her grave with the secret of being gay, until the referendum campaign for same-sex marriage in Ireland began.

For me, there was no first kiss; no engagement party; no wedding. And up until a short time ago no hope of any of these things. Now, at the age of 54, in a (hopefully) different Ireland, I wish I had broken out of my prison cell a long time ago. I feel a sense of loss and sadness for precious time spent wasted in fear and isolation.

Marriage Equality: Bring Your Family With You.

Turnout will be the key

It is a condition of the Irish constitution that Ireland has to hold a referendum in order to change it.

But voting is not compulsory in Ireland. And Ireland does not allow citizens to vote from abroad. Many many younger people are travelling back for the historic vote.

One of the recent polls from Ipsos found that 71% of 18- to 24-year-olds say they intend to vote yes and 15% no. By contrast, among the over-65s, 52% intend to vote no and 34% yes.

If there is a low turnout on Friday, the outcome could be much closer than suggested in polls, as older age groups are generally more likely to vote.

Memories of the 1995 divorce referendum, and how close that result was despite the polls predicting an easy Yes victory, will be weighing on both sides ahead of Friday’s vote.

Even so, the Yes campaign remains quietly confident that enough Irish people have made up their minds to support the change.

Whatever the outcome, the world will be waiting and watching Ireland for the result on Saturday.